Epoxy resins are cured with various curing agents to yield cured products generally excellent in properties such as mechanical properties, water resistance, chemical resistance, heat resistance and electrical properties, and are used in wide fields associated with materials such as adhesives, coating compositions, laminates, molding materials and casting materials. In applications as materials such as semiconductor sealants, heat resistance is required and accordingly cresol novolac epoxy resins are widely used. As surface mounting has prevailed, frequently semiconductor packages are directly exposed to high temperatures during reflow soldering, and additionally, as consciousness in environmental issues has recently been raised, lead-free solders have been used in semiconductor mounting in increasing cases. Such lead-free solders are higher in melting temperature by about 20° C. (melted at about 260° C.) than conventional solders, and consequently provide far higher possibilities of package crack occurrence during reflow soldering than conventional semiconductor sealants. With such circumstances as background, a biphenyl novolac epoxy resin has been proposed as an epoxy resin having excellent performances in such properties as heat resistance, moisture resistance and shock resistance (see Patent Document 1). Additionally, as a technique to decrease the melt viscosity of such a biphenyl skeleton-containing epoxy resin, a crystalline epoxy resin having a higher concentration of a bifunctional component has been proposed (see Patent Document 2). It is to be noted that a proposal has already been made on a biphenyl skeleton-containing phenolic compound to be a useful raw material for the crystalline epoxy resin (see Patent Document 3).
Patent Document 1: JP-A-5-117350 (pp. 1 to 6)
Patent Document 2: JP-A-2002-338656 (pp. 1 to 5)
Patent Document 3: JP-A-2002-322110 (pp. 1 to 3)